Online auctions allow users to post items to sell and/or view items for sale posted by other users. There may be various different auction platforms, each built with different technologies, e.g., web technologies, which may make them incompatible with one another. For example, a user may post a car for sale on multiple auction platforms, but when a bid for the car is received on an auction platform, the bid information may not be transmitted or shared with the other auction platforms where the car is posted for sale.